If we're going with this analogy, why not just put more raisins in the other bowl?
See, the problem with this analogy is it acts like there is a finite amount of stories. There is no limit to what stories can be created. But this analogy makes it seem like you can only use those stories already in that bowl.
If Netflix wanted to create a fantasy TV series with diverse casting, why not make one based off of African folklore, or Asian?
Also, this analogy only pays attention to stories in western countries. According to the author of this tumblr post, are those the only stories that matter? Are fantasy stories based in cultures influenced by Asia or Africa not as good? Why not take a story written by an African or Asian author, and adapt that?